Uniaxial-stress dependence of the first-order Raman spectrum of rutile. II. Model calculation

Abstract

We calculate the effect of uniaxial stress on the first-order Raman spectrum of rutile (${\mathrm{TiO}}_2$). We use a rigid-ion model fitted with axially symmetric tensor forces. All interactions are restricted to the first nearest neighbors and the change in the Coulomb part of the potential is neglected. The stress-induced change in the repulsive (short-range) interaction permits us (i) to account for the magnitude and sign of all experimentally determined deformation potentials and (ii) to identify (in terms of the four different bounds which define the rutile structure) the most important interaction which rules the frequency shift of a given Raman mode.